Drug & supplement interaction

Ashitaba + Fosphenytoin

Fosphenytoin brand name: Cerebyx.

No Known Interaction
Medically reviewed by · Updated June 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Ashitaba and Fosphenytoin in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first.

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Interaction report

Ashitaba and Fosphenytoin

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Fosphenytoin and Ashitaba in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Ashitaba safety at a glance

Ashitaba overall Use caution Likely safe as a food, but supplement safety has not been well studied.
Pregnancy Avoid Not enough safety data, so avoid concentrated supplements during pregnancy.
Breastfeeding Avoid Not enough safety data, so avoid concentrated supplements while breastfeeding.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Fosphenytoin and Ashitaba? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Fosphenytoin

Interactions in our licensed database are recorded against drug classes, not just single drug names. Fosphenytoin is filed under 11 classifications — including cytochrome p450 2c9 (cyp2c9) inducers, anticonvulsants, cytochrome p450 2c19 (cyp2c19) inducers. Ashitaba has documented interactions with 1 drug class — the most serious being cytochrome p450 1a2 (cyp1a2) substrates (moderate) — and none of Fosphenytoin’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Ashitaba Does Interact With Other Medications

Ashitaba has 186 moderate known drug interactions in our database — Fosphenytoin isn’t one of them. If you take anything else, check it against the full list below.

Moderate 186 No known interaction 2,644 (incl. Fosphenytoin)
Taking anything else?

Check Another of Your Medications Against Ashitaba

Covers the 2,830 medications we’ve checked against Ashitaba. Pick one to open its full report.

What to actually watch for

What Fosphenytoin’s Own FDA Label Lists

This is not an interaction — none of it involves Ashitaba. These are the most notable effects listed in the ADVERSE REACTIONS section of Fosphenytoin’s own FDA label, for the medication by itself. Knowing the drug’s own list makes it easier to work out the likely cause if something new turns up while you take both. 10 of them are worth acting on rather than waiting out — marked below.

  • Loss of vision Worth acting on
  • Hearing loss Worth acting on
  • A bowel blockage Worth acting on
  • Pain or burning when passing urine Worth acting on
  • Muscle weakness Worth acting on
  • Memory problems Worth acting on
  • Dehydration Worth acting on
  • Trouble swallowing Worth acting on
  • Trouble passing urine Worth acting on
  • High potassium Worth acting on

Showing the 10 most notable of 72 label-listed effects — ranked by how unusual each one is across medicines generally, with serious effects weighted up.

From the ADVERSE REACTIONS section of the FDA label for Fosphenytoin. Read the label on DailyMed › Ashitaba’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no Ashitaba side to compare — that is a limit of the record, not a statement that Ashitaba has no side effects.

Everything else you take

See Every Supplement That Interacts With Fosphenytoin

This page covers Ashitaba only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fosphenytoin page lists 205 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: 1,4-butanediol (major), American Hellebore (major), Arsenic (major), Beer (major) and Cesium (major).

By severity: 14 major · 172 moderate · 19 minor.

From our pharmacist’s overview on the Fosphenytoin page

“St. John's wort is the entry I would flag first with fosphenytoin (Cerebyx).”

Reviewed by 2 · Jul 18, 2026

Open the Fosphenytoin interaction page

One more smart check

Taking Ashitaba as Part of a Dietary Supplement Product? Check It for Interactions

We hold 41 real supplement products containing Ashitaba, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Ashitaba. Even though Ashitaba itself has no known interaction with Fosphenytoin, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Ashitaba and Fosphenytoin Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Ashitaba
Top half

#460 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Fosphenytoin
Top half

#1,086 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Ashitaba reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Ashitaba and Fosphenytoin records this page draws on were last updated June 22, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Ashitaba

What is Ashitaba?

Ashitaba
  • General wellness and longevity
  • Antioxidant support
  • Heart and cholesterol health
  • Digestive and stomach support
  • Anti-inflammatory

Ashitaba is a leafy plant from Japan that is eaten as a vegetable and taken as a supplement for general health, antioxidant, and heart benefits. Most of the supporting research comes from laboratory and animal studies, so its real benefits in people are still uncertain. It appears generally well tolerated as a food, but talk to your pharmacist or doctor before using concentrated supplements.

Angelica keiskei · Apiaceae · Leaves, stems, and roots · Tea, capsules, powder, dried leaves, fresh vegetable, juice

An interaction check asks whether these two react with each other — it does not ask whether Ashitaba is a good idea for someone in your situation. Here is what our Ashitaba record says about it on its own.

Ashitaba: dosing

There is no well-established, standardized dose for Ashitaba supplements. Studies have used different forms and amounts, so a single "correct" dose has not been set.If you choose to use an Ashitaba product, follow the directions on the label and do not exceed the recommended amount.

From our Ashitaba monograph — the full record covers uses, side effects and every documented interaction.

Read the full Ashitaba monograph & all interactions
Medication

About Fosphenytoin Injection

What Is Fosphenytoin Injection Used For?

Brand name: Cerebyx

Fosphenytoin injection is used to treat generalized tonic-clonic status epilepticus (a prolonged, life-threatening seizure emergency) and to prevent or treat seizures that occur during or after brain surgery. It is given by intravenous (IV) or intramuscular (IM) injection in a hospital or clinical setting.

It can also be used short-term as a substitute for oral phenytoin when a patient cannot take medicine by mouth. This use is temporary — as soon as oral phenytoin is possible again, it should replace the injection.

See full Fosphenytoin Injection drug information
Keep checking

Other Drugs & Ashitaba

Browse every other medication we’ve checked against Ashitaba — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
186Moderate
0Minor
2,643No known interaction
186 Moderate 2,643 No interaction
Moderate

186 interactions

Showing 60 of 186 moderate interactions — see all 186 on the Ashitaba page.

No interaction 2,643 drugs checked — show the list

We also checked Ashitaba against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,643 medications checked with no known interaction — see the full Ashitaba list.

See the full Ashitaba interactions page
See every supplement checked against Fosphenytoin, ranked by severity
Evidence & sources

Ashitaba References

The 2 references that drive our Ashitaba monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Kwon D, Yoon S, Carter O, Bailey GS, Dashwood RH. Antioxidant and antigenotoxic activities of Angelica keiskei, Oenanthe javanica and Brassica oleracea in the Salmonella mutagenicity assay and in HCT116 human colon cancer cells. Biofactors. 2006;26(4):231
  2. Noh HM, Ahn EM, Yun JM, Cho BL, Paek YJ. Angelica keiskei Koidzumi extracts improve some markers of liver function in habitual alcohol drinkers: a randomized double-blind clinical trial. J Med Food. 2015;18(2):166-72.

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Ashitaba and Fosphenytoin Together: Common Questions

Is it safe to take Ashitaba with Fosphenytoin?
We do not list a known interaction between Ashitaba and Fosphenytoin. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
How was the Ashitaba and Fosphenytoin combination checked?
Interactions in our licensed database are recorded against drug classes. Fosphenytoin is filed under 11 classifications, and Ashitaba has documented interactions with 1 drug class — none of Fosphenytoin's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Ashitaba interact with any other medications?
Yes. Ashitaba has 186 documented drug interactions in our database — Fosphenytoin is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Fosphenytoin interact with any supplements?
Yes. Fosphenytoin has documented interactions with 205 supplements in our database — Ashitaba is not one of them. The Fosphenytoin interaction page linked on this page lists every one, ranked by severity.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Where next

Keep Exploring

Ashitaba monograph Uses, safety profile, and every drug interaction in one place Fosphenytoin Injection drug information The full plain-English guide to this medication Fosphenytoin supplement interactions Every supplement checked against Fosphenytoin, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 2 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Fosphenytoin and Ashitaba?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.